Provision of support in underground mine workings

ABSTRACT

The invention provides a bag for spacing apart walls in an underground mine working, and including opposed load-bearing walls of flexible sheet material, each defining a substantially centrally located opening and an open-ended radial slot extending between and intersecting the central opening and outer periphery of the load-bearing wall, the openings and slots of the load-bearing walls being in register. There is an intermediate wall of flexible sheet material extending between the load-bearing walls and connected thereto substantially along the entire periphery of each load-bearing wall. A charging connector through the wall is for connection to a source of flowable substance under pressure for charging the bag therewith, to expand the bag by displacing the load-bearing walls away from each other. The invention also provides an installation and method which employ the bag to space the walls apart.

[0001] THIS INVENTION relates to the spacing apart of walls in an underground mine working. In particular, it relates to a bag for use in spacing apart a pair of opposed walls in an underground mine working, for example, a hanging wall and a foot wall of a stope forming part of the underground mine working; to an installation spacing apart a pair of opposed walls in an underground mine working; and to a method of spacing apart walls in an underground mine working.

[0002] The invention provides a bag for use in spacing apart a pair of opposed walls in an underground mine working, which bag includes:

[0003] a pair of opposed load-bearing walls of flexible sheet material, each load-bearing wall defining a substantially centrally located opening and an open-ended radial slot which extends between and intersects both the central opening and the outer periphery of the load-bearing wall, the openings and the slots of the load-bearing walls being in register;

[0004] an intermediate wall of flexible sheet material, the intermediate wall extending between the load-bearing walls and being connected to each load-bearing wall substantially along the entire periphery of each load-bearing wall; and

[0005] a charging connector through a wall of the bag, for connection to a source of flowable substance under pressure for charging the interior of the bag therewith, to expand the bag by displacing the load-bearing walls away from each other, to provide an expanded bag having a centrally located passage extending therethrough from one load-bearing wall to the other, and an open-ended space intersecting and extending between the centrally located passage and the outer periphery of the bag.

[0006] By the entire periphery of each load-bearing wall is meant not only the outer periphery of the load-bearing wall, but also its inner periphery along the edge of its opening and its periphery along the edges of its slot.

[0007] Differently defined, the invention provides, in a bag for use in spacing apart a pair of opposed walls in an underground mine working, the bag being of the type having walls of flexible sheet material and having a charging connector for connection to a source of flowable substance under pressure to dilate the bag, the improvement whereby the walls of the bag comprise:

[0008] a pair of opposed load-bearing walls, each load-bearing wall having a substantially centrally located opening and an open-ended slot which intersects, and extends radially between, the centrally located opening and the outer periphery of the load-bearing wall, the openings and slots of the load-bearing walls being in register; and

[0009] an intermediate wall which extends between the load-bearing walls and is connected to each load-bearing wall substantially along the entire periphery of each load-bearing wall, so that, upon expansion of the bag by charging of the bag through the charging connector with a flowable substance, the peripheries of the load-bearing walls are displaced away from each other.

[0010] The expanded bag will thus, when one of the load-bearing walls is viewed face-on, have a substantially centrally located passage extending through the bag from one load-bearing wall to the other, and an open-ended space intersecting and extending between the centrally located passage and the outer periphery of the bag.

[0011] The intermediate wall may have a width, in a direction from one said load bearing wall to the other, which is constant and has a value of 5-200 cm, preferably 15-30 cm.

[0012] In particular, the bag may include a restraining arrangement for restraining the bag to inhibit widening of the slots by movement of opposite sides of the slots away from each other in response to expansion of the bag. In one embodiment of the invention, for example, the restraining arrangement includes a fastening mechanism for fastening together portions of the intermediate wall separated by the open-ended space.

[0013] More particularly, the restraining arrangement may comprise at least one pair of ties, the ties of each pair being anchored to the intermediate wall at respective positions selected so that the ties of the pair can be tied together to inhibit said widening of the slots. In a particular embodiment of the invention, the bag is provided with a plurality of pairs of ties, the pairs being spaced in series and the series extending, in a direction across the width of the intermediate wall, from one said load-bearing wall to the other.

[0014] The flowable substance may be any suitable flowable substance selected from those known in the art, and such flowable substances include water an flowable grouts or slurries, in particular flowable cementitious grouts or slurries, in which cementitious solids are slurried with water.

[0015] The bag may be porous, being at least partially impervious to the solids in a cementitious slurry and being pervious to the water in such slurry, thus being a so-called weeping bag; or the bag may instead be impervious to both said solids and to water, so that the bag is not a weeping bag.

[0016] In the latter case, the bag may comprise a porous outer layer and a water-impervious bladder which lines the outer layer and is located inside the outer layer, the charging connector being a non-return inlet valve leading from the exterior of the outer layer into the interior of the bladder.

[0017] When the bag is porous or has a porous outer layer, the bag or layer may be of a woven polymeric plastics material, for instance being woven propylene, the porous intermediate wall being connected to the porous load-bearing walls by stitching.

[0018] The invention extends to an installation spacing apart a pair of opposed walls of an underground mine working, which installation includes:

[0019] an elongated strut extending between said opposed walls of the underground mine working, with ends of the strut respectively abutting said opposed walls of the underground mine working and with the strut under compression; and

[0020] a plurality of bags as claimed in claim 1, received on the strut, the bags being arranged face-to-face in series with one another with the load-bearing walls of adjacent bags in abutment, the series extending along the strut from one said wall of the underground mine working to the opposed wall of the underground mine working, each bag containing a solid substance under compression whereby the bag is at least partly expanded, and the strut passing through the centrally located openings of the load-bearing walls of each bag.

[0021] The opposed walls of the underground mine working may be a foot wall and a hanging wall of a stope forming part of the underground mine working, the strut and the series of bags extending upwardly from the foot wall to the hanging wall and supporting the hanging wall above the foot wall.

[0022] Instead, the opposed walls of the underground mine working may be a pair of opposed side walls of a stope, the strut and series of bags extending more or less horizontally between said side walls.

[0023] In particular, each bag may comprise an annulus which is interrupted by a radially extending space, opposed parts of the intermediate wall of the bag, at the radially outer end of the space, being fastened together to inhibit widening of the space in response to expansion of the bag.

[0024] The bags may be received on the strut in an arrangement such that the spaces of successive bags are angularly offset relative to each other so that said spaces are out of register with each other when viewed lengthwise relative to the series.

[0025] The invention further provides a method of spacing apart walls in an underground mine working in which a strut is held captive and under compression by abutment of ends of the strut respectively against a pair of opposed walls forming part of the underground mine working, the strut extending between said walls, the method including the steps of:

[0026] positioning a plurality of bags as claimed in claim 1, in series on the strut so that the strut is received in the centrally located openings of the load-bearing walls of each bag; and

[0027] at least partially expanding each bag by means of a flowable substance under pressure to place each bag under compression and to cause it to assume an expanded shape.

[0028] The method may include the step, prior to the expanding, of fastening together opposed parts of the intermediate wall at or adjacent the outer periphery of the bag, to restrain and inhibit moving apart of said opposed parts in response to the expanding of the bag.

[0029] The method may include the step of positioning the strut between a foot wall and a hanging wall in a stope forming part of the underground mine working, so that the strut extends upwardly from the foot wall to the hanging wall of the stope, and so that the bags form a stacked series which extends upwardly from the foot wall to the hanging wall.

[0030] In particular, the step of positioning the bags may be such that they are arranged with the spaces of successive bags angularly offset relative to each other so that said spaces are out of register with each other when viewed lengthwise relative to the series.

[0031] The invention will now be further described, by way of example, with reference to the accompanying diagrammatic drawings, in which:

[0032]FIG. 1 is a schematic three-dimensional view of a bag for use in spacing apart a hanging wall and a foot wall in an underground mine working, in accordance with the invention;

[0033]FIG. 2 is a view corresponding to FIG. 1, but rotated through 180° about a vertical axis; and

[0034]FIG. 3 is a schematic side elevation of an installation in accordance with the invention which includes a plurality of the bags of FIG. 1, spacing apart a hanging wall and a foot wall of a stope in an underground mine working in accordance with the method of the invention.

[0035] In the drawings, reference numeral 10 generally indicates a bag for use in supporting a hanging wall 12 over a foot wall 14 (FIG. 3) in an underground mine working, in accordance with the invention.

[0036] The bag 10 has walls of flexible sheet material, in this case woven polypropylene, and a valve 16 forming a charging connector for connection to a source (not shown) of flowable substance under pressure to expand the bag 10. The bag 10 has a pair of load-bearing walls 18, and an intermediate wall 20 extending between the load bearing walls 18.

[0037] Each load-bearing wall 18 is more or less square in outer peripheral outline, when viewed face-on, and is provided with a part-circular opening 22 which is located centrally in the load-bearing wall 18. It should be appreciated that, in other examples, the outer peripheral outline of the load-bearing walls 18 need not be square, but can have any desired shape, such as being circular, in which case the bag 10 is broadly annular or doughnut-shaped. An open ended slot 24 extends radially between the central opening 22 and the outer periphery 26 of each load-bearing wall 18, such that the slot 24 intersects both the opening 22 and the outer periphery 26 of the load-bearing wall 18. Each load-bearing wall 18 thus has an entire periphery constituted by its outer periphery 26 and its inner periphery 28, which inner periphery 28 extends along and includes both the edge of the opening 22 and the opposed edges of the slot 24. This provides the bag, when expanded as shown in FIGS. 1 and 2, with a centrally located passage extending therethrough from one wall 18 to the other; and an open ended space intersecting and extending between the centrally located passage and the outer periphery of the bag, the outer periphery of the bag being provided by that part of the wall 20 which provides the square outer peripheral outline of the bag, the inner periphery of the bag, in contrast, being the part of its periphery which defines the space and the centrally located passage.

[0038] The load bearing-walls 18 are connected together by the intermediate wall 20 which extends between the load-bearing walls 18, the intermediate wall 20 being connected to both load-bearing walls 18 along the entire periphery of each load-bearing wall 18 by stitching 30. The intermediate wall 20 comprises a single continuous panel extending along the entire periphery, i.e. both the inner periphery 28 and the outer periphery 26, of the bag 10, so that the interior of the bag 10 is sealed off. However, in other examples of the invention, the intermediate wall 20 may consist of a plurality of panels which are connected together end-to-end. The width W of the intermediate wall 20, in a direction normal to and from the one load-bearing wall 18 to the other, is about 25 cm.

[0039] The valve 16 is in the form of a non-return inlet valve which is provided in, and extends through, a portion of the intermediate wall 20 which is diametrically opposed, relative to the central passage, to the open-ended space.

[0040] The bag 10 is also provided with a restraining arrangement in the form of three pairs 36 of ties 38, each tie 38 being anchored to the intermediate wall 20 at the end of the open-ended space remote from the central passage. The pairs of ties 38 are arranged in a series extending from one load-bearing wall 18 to the other, across the intermediate wall 20 at the outer end of the open-ended space, the ties 38 of each pair respectively being on opposite sides of said outer end. Thus, the anchorages of the ties 38 of each pair 36 are respectively located on opposite sides of the open-ended space, with the ties 38 of each pair adjacent a load-bearing wall 18 respectively being anchored along opposite edges of the associated slot 24, and having end portions 39 projecting from the inner ends of said edges and providing a further pair of ties adjacent the central opening 22. It will be appreciated that in use, the further pair of ties 39 will further resist undesired widening of the open ended space, at its end adjacent the central passage. In other examples of the invention, instead of ties 38, the bag 10 can be provided with a restraining arrangement in the form of webbing, hook-and-loop fasteners such as those known under the Trade Mark “Velcro”, or any other suitable restraining arrangement.

[0041] In use, a plurality of the bags 10 is used in combination with a support prop or strut 40 which is held captive between the hanging wall 12 and the foot wall 14 (FIG. 3) of a stope 42 in an underground mine working by abutment of an upper end 44 and a lower end 46 of the strut 40 respectively against the hanging wall 12 and the foot wall 14, with the strut 40 under compression.

[0042] The bags 10 are positioned on the strut 40 such that the strut 40 is received in the central passage of each bag 10, the bags 10 extending in series in a stacked arrangement along the strut 40. Thereafter, the ties 38 of each pair 36 are fastened together. The bags 10 are arranged on the strut 40 such that the open-ended spaces and slots 24 of successive bags 10 are offset by 180°, being out of register, in plan view, extending in diametrically opposed directions from the central passage.

[0043] The charging connectors 16 of the bags 10 are then connected in turn to the source of flowable substance under pressure for charging of the bag 10 with the flowable substance to expand the bag 10. In this example, the flowable substance is cementitious slurry or grout, the walls 18, 20 of the bag 10 being pervious to water in the slurry but impervious to cementitious solids in the slurry, so that the bags 10 are so-called weeping bags. In other examples of the invention, the flowable substance can be a slurry with water of any other suitable particulate settable cementitious material, or indeed it can be a liquid, such as water. In the case where the flowable substance is water, the bags 10 should of course be impervious to water, to form so-called non-weeping bags. The bags 10 are expanded one by one, starting with a lowermost bag 10 and ending with an uppermost bag 10.

[0044] Upon expansion of each bag 10, the load-bearing walls 18 of the bag 10 are displaced away from each other and the intermediate wall 18 is stretched taut, so that the entire peripheries of the load-bearing walls 18 are vertically spaced apart. During expansion of each bag 10, widening of the open-ended space of the bag 10 by displacement of portions of the intermediate wall 18 which face each other across the open-ended space away from each other, which could lead to undesired disengagement or displacement of the bag 10 from the strut 40, is inhibited by the fastened-together ties 38.

[0045] The bags 10 are charged with grout or slurry such that the uppermost bag 10 abuts against the hanging wall 12 and exerts a desired supporting force on the hanging wall 12, the bags being placed under compression. The grout in the bags 10 is then allowed to set, so that the stacked bags 10 and the strut 40 form a composite support installation 48 under compression for supporting the hanging wall 12 above the foot wall 14.

[0046] In a further use, the bag 10 can be retro-fitted on an existing support installation (not shown) which comprises a support strut surrounded by a stacked series of doughnut-shaped bags, to replace any doughnut-shaped bag which has burst or otherwise failed; and bags 10 can if desired, be stacked around struts 40 which were originally installed without bags.

[0047] It is an advantage of the invention as described with reference to the drawings that the bags 10 can be stacked around on an existing support strut 40 which has already been positioned between the hanging wall 12 and foot wall 14 to form a composite support installation 48. The bag 10 is constructed such that it can be expanded to a height which is sufficiently great to permit the formation of a stacked arrangement which extends from the foot wall 14 to the hanging wall 12 by an acceptably small number of bags 10.

[0048] As the bags 10 have substantially parallel, more or less flat load-bearing faces 18 when charged, the stacked arrangement of bags 10 is also more stable than stacked arrangements of some existing bags of which the load-bearing walls are directly connected together along their edges, so that they are convex when charged. 

1. A bag for use in spacing apart a pair of opposed walls in an underground mine working, which bag includes: a pair of opposed load-bearing walls of flexible sheet material, each load-bearing wall defining a substantially centrally located opening and an open-ended radial slot which extends between and intersects both the central opening and the outer periphery of the load-bearing wall, the openings and the slots of the load-bearing walls being in register; an intermediate wall of flexible sheet material, the intermediate wall extending between the load-bearing walls and being connected to each load-bearing wall substantially along the entire periphery of each load-bearing wall; and a charging connector through a wall of the bag, for connection to a source of flowable substance under pressure for charging the interior of the bag therewith, to expand the bag by displacing the load-bearing walls away from each other, to provide an expanded bag having a centrally located passage extending therethrough from one load-bearing wall to the other, and an open-ended space intersecting and extending between the centrally located passage and the outer periphery of the bag.
 2. A bag as claimed in claim 1, in which the intermediate wall has a width, in a direction from one said load bearing wall to the other, which is constant and has a value of 5-200 cm.
 3. A bag as claimed in claim 1, which includes a restraining arrangement for restraining the bag to inhibit widening of the slots by movement of opposite sides of the slots away from each other in response to expansion of the bag.
 4. A bag as claimed in claim 3, in which the restraining arrangement comprises at least one pair of ties, the ties of each pair being anchored to the intermediate wall at respective positions selected so that the ties of the pair can be tied together to inhibit said widening of the slots.
 5. A bag as claimed in claim 4, in which the bag is provided with a plurality of pairs of ties, the pairs being spaced in series and the series extending, in a direction across the width of the intermediate wall, from one said load-bearing wall to the other.
 6. A bag as claimed in claim 1, in which the bag is porous, being at least partially impervious to the solids in a cementitious slurry and being pervious to the water in such slurry.
 7. A bag as claimed in claim 1, in which the bag is impervious to both said solids and to water.
 8. A bag as claimed in claim 7, which comprises a porous outer layer and a water-impervious bladder which lines the outer layer and is located inside the outer layer, the charging connector being a non-return inlet valve and leading from the exterior of the outer layer into the interior of the bladder.
 9. A bag as claimed in claim 1, in which the bag is of a woven polymeric plastics material.
 10. A bag as claimed in claim 9, in which the intermediate wall is connected to the load-bearing walls by stitching.
 11. An installation spacing apart a pair of opposed walls in an underground mine working, which installation includes: an elongated strut extending between said opposed walls of the underground mine working, with ends of the strut respectively abutting said opposed walls of the underground mine working and with the strut under compression; and a plurality of bags, each bag including a pair of opposed load-bearing walls of flexible sheet material, each load-bearing wall defining a substantially centrally located opening and an open-ended radial slot which extends between and intersects both the central opening and the outer periphery of the load-bearing wall, the openings and the slots of the load-bearing walls being in register, an intermediate wall of flexible sheet material, the intermediate wall extending between the load-bearing walls and being connected to each load-bearing wall substantially along the entire periphery of each load-bearing wall, and a charging connector through a wall of the bag, for connection to a source of flowable substance under pressure for charging the interior of the bag therewith, to expand the bag by displacing the load-bearing walls away from each other, to provide an expanded bag having a centrally located passage extending therethrough from one load-bearing wall to the other, and an open-ended space intersecting and extending between the centrally located passage and the outer periphery of the bag, the bags received on the strut, the bags being arranged face-to-face in series with one another with the load-bearing walls of adjacent bags in abutment, the series extending along the strut from one said wall of the underground mine working to the opposed wall of the underground mine working, each bag containing a solid substance under compression whereby the bag is at least partly expanded, and the strut passing through the centrally located openings of the load-bearing walls of each bag.
 12. An installation as claimed in claim 11, in which the opposed walls of the underground mine working are a foot wall and a hanging wall of a stope forming part of the underground mine working, the strut and the series of bags extending upwardly from the foot wall to the hanging wall and supporting the hanging wall above the foot wall.
 13. An installation as claimed in claim 11, in which the opposed walls of the underground mine working are a pair of opposed side walls of a stope, the strut and series of bags extending more or less horizontally between said side walls.
 14. An installation as claimed in claim 11, in which each bag comprises an annulus which is interrupted by a radially extending space, opposed parts of the intermediate wall of the bag, at the radially outer end of the space, being fastened together to inhibit widening of the space in response to expansion of the bag.
 15. An installation as claimed in claim 11, in which the bags are received on the strut in an arrangement such that the spaces of successive bags are angularly offset relative to each other so that said spaces are out of register with each other when viewed lengthwise relative to the series.
 16. A method of spacing apart a pair of opposed walls in an underground mine working in which a strut is held captive and under compression by abutment of ends of the strut respectively against a pair of opposed walls forming part of the underground mine working, the strut extending between said walls, the method including the steps of: positioning a plurality of bags in series on the strut, each bag including a pair of opposed load-bearing walls of flexible sheet material, each load-bearing wall defining a substantially centrally located opening and an open-ended radial slot which extends between and intersects both the central opening and the outer periphery of the load-bearing wall, the openings and the slots of the load-bearing walls being in register, an intermediate wall of flexible sheet material, the intermediate wall extending between the load-bearing walls and being connected to each load-bearing wall substantially along the entire periphery of each load-bearing wall, and a charging connector through a wall of the bag, for connection to a source of flowable substance under pressure for charging the interior of the bag therewith, to expand the bag by displacing the load-bearing walls away from each other, to provide an expanded bag having a centrally located passage extending therethrough from one load-bearing wall to the other, and an open-ended space intersecting and extending between the centrally located passage and the outer periphery of the bag, the positioning of the bags on the strut being so that the strut is received in the centrally located openings of the load-bearing walls of each bag; and at least partially expanding each bag by means of a flowable substance under pressure to place each bag under compression and to cause it to assume an expanded shape.
 17. A method as claimed in claim 16, which includes the step, prior to the expanding, of fastening together opposed parts of the intermediate wall at or adjacent the outer periphery of the bag, to restrain and inhibit moving apart of said opposed parts in response to the expanding of the bag.
 18. A method as claimed in claim 16, which includes the step of positioning the strut between a foot wall and a hanging wall in a stope forming part of the underground mine working, so that the strut extends upwardly from the foot wall to the hanging wall of the stope, and so that the bags form a stacked series which extends upwardly from the foot wall to the hanging wall.
 19. A method as claimed in claim 16, in which the step of positioning the bags is such that they are arranged with the spaces of successive bags angularly offset relative to each other so that said spaces are out of register with each other when viewed lengthwise relative to the series. 